It's all but impossible to find out anything about the many deadly drone strikes launched in Afghanistan — and it's about to get worse.

On the afternoon of September 7 last year, in the Watapur region of Afghanistan’s Kunar province, a farmer named Miya Jan heard a buzzing overhead. He looked up to see a drone, he told the Los Angeles Times, and minutes later, he heard an explosion.

Reaching the site of the blast, he saw a mangled vehicle — which he soon realized belonged to his cousin. Among the bodies, he recognised his brother and his brother’s family. "There were pieces of my family all over the road," he said. "I picked up those pieces from the road and from the truck and wrapped them in a sheet to bury them."

There were claims and counter-claims in the aftermath of the attack. Afghan officials said the vehicle had contained at least eight civilians, and possibly as many as 11. But the International Security Assistance Force (ISAF) said the strike killed 10 "enemy forces." Still, a spokesman told the New York Times that ISAF would investigate.

The UN Assistance Mission in Afghanistan (UNAMA) also investigated. After interviewing more than 50 sources, it concluded that the vehicle was carrying six "insurgents" when it was struck — along with 11 civilians, including four women and four children. A 4-year-old girl was seriously wounded.

Faced with this claim, ISAF initially "denied the possibility of civilian casualties," UNAMA later reported. Pressed further, ISAF eventually confirmed the deaths of a woman and child, and "would not rule out the possibility of another woman’s death."

An ISAF spokesman told us that ISAF took precautions to avoid non-combatant deaths. "ISAF identified a target individual in a vehicle and followed him to an area remote from villages and apparent civilians," the spokesman said. "In spite of persistent observation, unknown to ISAF there were at least three civilians located in the vehicle with the target.

“Although ISAF's engagement was successful against the insurgent target, regrettably the strike resulted in three other casualties."

ISAF's internal casualty records for September 2013, which we obtained, show that despite UNAMA's strong evidence of there having been 10 civilian deaths, ISAF still records just three non-combatants killed in the incident. The other deaths are not acknowledged — and in the black-and-white of the spreadsheet, even the possibility of further civilian deaths vanishes.

This isn’t the only incident in which ISAF appears to have underreported non-combatant casualties. In 2010, Science reporter John Bohannon embedded with ISAF's civilian casualty tracking unit, and was provided with its data. He found the organization's estimates were often far below UNAMA's; for airstrikes in 2009 and 2010, they were 74 percent lower.

An ISAF commander explained the organization cannot access all provinces, and its assessments are sometimes carried out from the air. "We only count that which we see," he told Bohannon. "You can do a tremendous amount of forensics… [but] seldom do we see the actual bodies."

The apparent initial reluctance to acknowledge civilian casualties in the aftermath of the Watapur strike would seem to run counter to stated military strategy. In August 2010, a month after he assumed command of international forces in Afghanistan, General David Petraeus issued instructions on how ISAF should manage the counter-insurgency.

He ordered troops to, "Be first with the truth…. Pre-empt rumors. Get accurate information to the chain of command, to the Afghan people, and to the press as soon as possible…. Acknowledge setbacks and failures, including civilian casualties, and then state how we’ll respond and what we’ve learned."

UNAMA found that 45 civilians were killed in drone strikes in 2013, accounting for more than a third of total civilian deaths in airstrikes — and more than three times the 2012 toll.

Elizabeth Minor, a senior researcher at the Oxford Research Group, a think tank that has studied the recording of casualties in conflicts around the world, echoes what Petraeus told the troops. "The transparent recording of casualties of conflict is essential, no matter what tactics or weapons are being used. It is needed to give recognition and understand the impact of violence, but also to evaluate the conduct and policies of conflict parties."

There are more drone attacks in Afghanistan than anywhere else in the world; the Watapur strike is one of more than 1,000 known to have hit the country in the past 13 years. Yet there is no public record of when and where these strikes took place — or who they killed. More is understood of America's campaigns in Pakistan, Yemen, and Somalia than about how drone use has evolved in Afghanistan.

The Bureau of Investigative Journalism and others have used open sources — media reports, court affidavits, NGO reports, and independent field investigations — to piece together a strike-by-strike picture of more than 450 strikes conducted in covert US campaigns, revealing at least 2,681 reported deaths, including 480 people described as civilians.

Reporting from Pakistan, Yemen, and particularly Somalia is fraught with danger and difficulty, and this is reflected in the available reporting. But viewed as a whole, these sources paint a picture of how drones are used, and how their use has evolved. For example, the data shows a striking fall in civilian casualties over the past five years in Pakistan.

But there is no such public record available for Afghanistan.

Airstrikes represent a tiny fraction of the horrendous cost to non-combatants of the violence in Afghanistan — 1 percent, according to UNAMA's latest report. In the first six months of 2014, the report documented more than 1,500 civilian deaths; crossfire from gun battles and roadside bombs were the leading causes.

But the information in the public domain raises troubling questions about the accuracy of drones when compared to other aircraft. UNAMA found that 45 civilians were killed in drone strikes in 2013, accounting for more than a third of total civilian deaths in airstrikes — and more than three times the 2012 toll. (In 2012, the most recent year for which data is available, about 1 in 5 of all air strikes were carried out by drones.)

And civilian deaths persist: UNAMA released data to us showing that in the first half of 2014, it had identified eight civilian deaths in drone strikes — a decline from last year’s total, but similar to 2012, when UNAMA recorded 16 non-combatants killed. The organization cautions that these figures may be underestimates.

Meanwhile, a 2013 study analyzing classified ISAF data found that drone strikes are significantly more likely to kill non-combatants than strikes carried out by other aircraft.

There is also the question of accountability. Unlike the covert campaigns, which are waged by the US alone, in Afghanistan two nations operate armed drones: the UK and the US. But there is a vacuum of information around which force conducted which strike.

The UK, which has carried out more than 300 drone strikes in the country, has consistently stated it is aware of only one incident in which non-combatants died: a March 2011 strike that killed four farmers. In December 2013, three months after the Watapur strike, then–Defence Secretary Philip Hammond reiterated this claim in a Guardian op-ed.

In contrast, the US has not publicly acknowledged having any part in the Watapur strike — or in the other 18 drone strikes that UNAMA found killed civilians in 2013. Nor is there any explanation as to why the level of accuracy apparently achieved by the UK is not matched by the US.

In Pakistan and Yemen, media reports and other sources help augment the lack of official information; there are accounts from the ground, local officials, and even sometimes unnamed US officials. But our analysis finds that in Afghanistan, many strikes likely go entirely unreported. Still more are reported by only a single source, or include only the vaguest details.

It’s not always clear whether an attack was launched from an aircraft or not, according to an analyst speaking on condition of anonymity. "The problem is that when something goes bang here, it’s a very confused place, so sometimes it’s not even clear if something was dropped from the sky or if it’s an IED — just something goes bang," he said.

We gathered reports of attacks in September 2013, identifying 34 airstrikes, including 10 drone strikes. Attacks described as drone strikes were significantly more likely to include claims of civilian casualties than other air strikes, but the reporting is just too sparse to draw firm conclusions.

As full operations draw down and forward operating bases that gather intelligence are closed, the risks to civilians mount, warns Rachel Reid, who leads research on Afghanistan and Pakistan at the Open Society Foundation.

"As the US withdraws from Afghanistan," she said, "[and] the networks of informants that provide human intelligence on potential targets is dismantled, the quality of intelligence that informs the strikes will degrade, making misidentifications and civilian casualties more likely."